Connecting mechanism fob demand



July 29, 1952 L. A. PAINE ETAL 1 R 23,529 CONNECTING MECHANISM FORDEMAND METERS Originai- Filed 001:. 26, 1946..

Reissuecl July 29, 1952 Manufacturing; Company, Lafayette; Ind;;acorporation of Illinois flriginal Nb. 2 ,482,192;aareasepreniber 27;1949,

Serial No; 705,946, October 26,1946.

Appli aticn ,fo'r' reissue October 4, 1951,- Serial No.

7 Claims; (01. 1"7'1'- s"4"') Matter enclosed in heavy" brackets ['15appears in the original patent but forms" no partof this reissuespecification: matter printed-" in italics indicatesthe additions" madeby reissue.'-

present invention, this-is now also accomplished with respect to"athermal demand attachmentf'or'a wattliour meter.

In the case of the thermal demand attach-=- ment, the problem is maderelatively compli-' cated by virtue of the relativelylarge number ofconnections which n'iust' be made and by virtue of the desirethat-variations in' the resistance ofthese connections have no effect onthe calibr'a---' tion of the demand meter, thus permitting" cali brationof the demand unit independently ofits application toa particular meter.With regard to the number of connection'srequired, it"is" not onlynecessary to provide avoltage connection for which purpose twoconnections'su'ffice; but is also necessary to connect boththe-heat'ei'g of the thermal unit', and sometimes a shunt in parallelwith each of them, in'the" circuit.- For each connection of this lattertype, series connec= tions-are required to be'inter'posedin a circuit-ofthe watthour meter. It" is highly desirable to uses. standard-meter caseas-far as possible and particularly to obtain a-compactnesswhichwill notrequire an enlarged-base. Furthermore, it is= very desirable thatthe'wattliourmeter beeasily restored to operabimy when the demandattachment has been removed; According to the pres'entinvention, theseries connections are accomplished in a very simple manner'through theaid of two'terminal plates in' parallel relation-- ship, separated by aninsulated spacer and slotted to slip' onto terminal screws, a shunt(when used) and the other necessary cornice-'- tions' being permanentlyconnected. to these two terminal plates. the connection for both oftheseterminal plates;

the screw itself engaging one" of the terminal.-

plates and exerting a force through it and. the insulating spacer toclamp the'other terminal plate against a connecting member. Of-cou'rse,the screw must be insulated from this connectingmember. Tightening thescrew when the terminal plates are not inserted thereunder makes thewatthour meter effective without 'thedemand meter;

The samescrew may tighten on: an enlargedscale showingthe details of theconnection and showing a typical circuit diagrammatically; and I Fig. 3'isjaoross section' taken approximately (in the line 3"'3*of Fig. 2'.

Although the law requires a full and" exact description of' at'l'ea'stone form of the invention;

such as that" whicli" follows; itis. of course, the purpose of a patentto cover each new inventive: concept therein no matter how it maylat'erbe,

disguisedby variations in ior'm' or additions of further improvements;and the appended claims are intended toaccomplish this purpose byparticularly poin in out: the parts, improvements, orj co'mbinations'inwhich theinventiv'e concepts un I f. the' illus'trated' form of theinvention, the combination meter is'carrie'd by a base plate ll which'is illustrated as a conventional plate of the socket typ'efof meter; theplate, with the meter carried" thereby, being-adapted to be pluggedinto'ameter' socket". A The base carriesa watthour meter assembly [2. Ademand" meter assembly I3 is preferably carried by the" watt'-' hourmeter assembly l2 so that the twomay be The baseplate l l, carries fourterminal blades [4 which are; ins'ulated from the" base" plate by s l ql The termin ad o from-the'front of thebase seen in Fig. lthrough thebase to farm blades with Which: the meter is plugged intofthe socket. IThejt'err'ninal blades Ill are, therefore, connectorsfor connecting themeter elements to the wiresdf the circuitbeing metered. a U y p V Thewatthour meter includes" at least on'e' 'icurrent coil indicateddmgrsm'mascauy at [1 'in Fig.

2." A typicalconnectio'n for such curre'nt coil l'l includes a lead-Wire or conductor It provided with aterm'inalfthrough whichscrew'l'ie'xtendsf forclamp'ing' the"terminal o'f conductor l8 a gain'st"conducto'r or" blade I I"; This is "a cams-camera:

d of connecting the current coil I! to connectors or terminal blades I4when there is no demand meter involved. In that instance the screw I9 isusually threaded directly to the terminal blade I4.

According to the present invention, it is desirable that this sameconnection be made when a demandmeter is not attached to the watthourmeter, but that the connection be readily altered when desired, toconnect a part of the demand meter circuit in series between theterminal blade I4 and the conductor I8. This may very readily beaccomplished by the structure shown in the drawings.

The illustrated form of demand meter is of the thermal type including athermal meter element 2|. As illustrated diagrammatically in Fig. 2,this thermal meter element has within it a pair of oppositely woundbimetallic coils 22, each connected at one end to the indicator shaft 23and to a fixed member 24 at the other end. The thermal unit 2I alsoincludes heaters 29. The heaters 26 are heated by the combined effectsof current from the secondary coil 21 of transformer 28 and current fromin the circuit being measured which is carried through lead wires 29.

The theory underlying the thermal demand meter is not a part of thepresent invention and is well known. It may be noted, however, that thesecondary coil 21 is responsive to the voltage in the metered circuitbeing energized by primary coil 3I connectedacross the circuit beingmeasured. The current in the circuit being measured which is supplied tothe thermal unit by leads 29 is divided between the two heaters 26. Whenthe expected current in the circuit being measured is heavier than itwould be desired to carry through the heaters 26, any predeterminedportion of the current may be shunted past these heaters by a shunt 32.It is essential that there be an exactly constant relationship betweenthe resistance of the path of the shunt 32 and the path of resistances25. Accordingly, the leads 29 are soldered or otherwise permanentlyconnected to the'shunt terminals 33.

As seen in Figs. 1 and 2, the shunt 32 may conveniently be a slimU-shaped strap of metal so that the terminals 33 Will lie close togetherand parallel to one another. They may then easily be separated andinsulated from one another by an insulator 34. Both the terminals 33 andthe insulator 34 are slotted so that they may jointly be slipped underthe heads of screw I9, and preferably also a second screw 36. When thescrew I9 is tightened, it clamps the various conductors and insulatorsas a pile so that, as seen in Fig. 2, the terminal blade I4 is incontact with one demand meter terminal 33 While the other demand meterterminal 33 is in contact with the terminal of conductor I B. I

In order that there be no short circuiting, it is necessary that screwI9 be adequately insulated. To this end it is connected with aninsulating bushing 31 which extends through all of the pile except,perhaps, the terminal of conductor I 8. The screw I9 is threaded into a[knot] nut or plate 38 which is insulated from terminal blade I4 by aninsulator 39.

It will be apparent from Fig. 2 that when the terminals 33 and theseparating insulator 34 are withdrawn fromthe screw I9, the screw I9 may[then] be screwed in further to clamp the terminal of conductor I8directly against the terminal blade I4. It is apparent from the drawingthat the bushings 37 are long enough so the one on screw 19 must beremoved, unless a metal plate or spacer is inserted between conductor 18and blade 14 before this screw is tightened. This will connect thecurrent coil H in the circuit independently of the demand meter when thede mand meter is not desired.

Inasmuch as permanency of connection is important between the shunt 32and the lead wires 29, the form of connection illustrated is preferred.As seen in Figs. 1 and 3, each of the terminal 33, which are preferablyformed of fairly heavy copper, are provided with an extension bent backto form a soldering loop 4!. The various lead Wires to be connectedthrough these terminals are soldered in these loops M where they areheld reliably by the combined effects of the soldering and the loop. Theterminals 33 are soldered directly to the shunt 32. It is preferablethat this soldering be made first and be made with a silver solder orother high-temperature solder so that this connection will not beaffected in soldering the lead wires in loops M with ordinary solderhaving a relatively low melting point.

Although the connections have been described with respect to one shunt32 and its associated parts, it should be understood that there wouldordinarily be two such shunts, the terminals 33 therefor being seen inFig. 1, at the left of the watthour meter assembly I2. By loosening allfour of the screws I9 and 36 and by loosening the supporting screws 42for the thermal meter assembly, the entire thermal meter assemblyincluding face plate I3 may be lifted off of the frame I2 of thewatthour meter assembly. There may also be voltage connections whichwill need to be disconnected by loosening screws 43. After removing thethermal meter assembly, the various screws may be tightened againwhereupon the watthour meter will be in a fully functioning condition.

It will be apparent that watthour meters may be sold and installedwithout the thermal demand unit and that subsequently the thermal demandmeter features may be attached thereto by a reverse of the simple mannerof disconnecting it just described. It may be necessary to substitute aslightly deeper glass cover when adding the thermal demand meterfeatures, but otherwise no change in the support or housing will berequired. It may be noted that 40 is a conductor strap forming part ofthe voltage connections for the meter. It and insulator 39 have beenomitted in Fig. l for clarity From the foregoing it is seen that acombination of watthour and demand meters is provided in which thewatthour meter may easily be rendered efiec'tive with or without thedemand meter and in which the demand meter may easily be removed from orapplied to or replaced on the watthour meter, the entire structure beingsup' ported by a conventional meter base plate. It may be noted in thisconnection that even if the bottom-connected type of meter base is used,it is preferred that it be provided with connectors at the position ofthe connectors I4, seen in the upper portion of Fig. 1, so that the samethermal demand meter may be applied thereto or removed therefrom atwill.

We claim:

1. A combination of a watthour meter and a thermal demand meterincorporating a shunt member and a demand meter circuit permanentlyconnected across the shunt member as a parallel unit, said combinationincluding a connector for connection to a wire of the-circuit beingmeasured, a watthour meter lead wire, and means for interposing saidparallel unit in series between said watthour meter lead and saidconnector, said means being adapted for ready separation from theconnector and watthour meter lead while maintaining the demand metercircuit connected across the shunt, said structure including a pair ofsubstantially parallel terminal plates to which the shunt and the demandmeter circuit are connected, an insulating spacer between said plates,and screw means for jointly clamping together the watthour meter lead incontact with one terminal plate, the insulating spacer, and the otherterminal plate in contact with the connector, said screw means beinginsulated between its ends and under one end so that in clamping saidparts together it does not connect the terminal plates to each other orthe watthour meter lead and connector to each other.

2. A combination of a watthour meter and a thermal demand meterincorporating a shunt member and a demand meter circuit permanentlyconnected across the shunt member, said combination including aconnector for connection to a wire of the circuit being measured, awatthour meter lead wire, and means for interposing the demand metercircuit in series between said watthour meter lead and said connector,said means being adapted for ready separation from the connector andwatthour meter lead while maintaining the demand meter'circuit connectedacross the shunt, said structure including a pair of substantiallyparallel terminal plates to which the demand meter circuit is connected,an insulating spacer between said plates, and screw means for jointlyclamping together the watthour meter lead in contact with one terminalplate, the insulating spacer, and the other terminal plate in contactwith the connector, said screw means being insulated between its endsand under one end so that in clamping said parts together it does notconnect the terminal plates to each other or the watthour meter lead andconnector to each other.

3. A combination of a watthour meter and a demand meter including aconnector for connection to a wire of the metered circuit, a watthourmeter lead conductor, a pair of demand meter circuit terminals separatedby an insulator and lying between the connector and the lead conductor,a screw passing through the conductor, the terminals, and the connectorfor clamping them together as a pile, said terminals and the insulatortherebetween being slotted with the slots correlated and opening on oneedge so that they may be removed together, and said screw then beingadapted to clamp the conductor and the connector together to effectuatethe watthour meter circuit.

4. A combination of a watthour meter and a demand meter including aconnector for connection to a wire of the circuit being measured, awatthour meter lead conductor, a pair of demand meter circuit terminalsseparated by an insulator and lying between the connector and the leadconductor, screw means for clamping together the conductor, theterminals, and the connector as a pile, said terminals being constructedand adapted to be removed together with the insulator therebetween, andsaid conductor and I 6 connector then being ward the other, and saidscrew means being constructed and adapted to clamp the conductor and theconnector together to efiectuate the watthour meter circuit.

5. A connecting mechanism including a connector for connection to a wireof the circuit being measured, a lead conductor, a pair of circuitterminals separated by an insulator and lying between the connector andthe lead conductor, screw means for clamping together the conductor, theterminals, and the connector as a pile, said terminals being constructedand adapted to be removed together with the insulator therebetween, andsaid conductor and connector then being relatively movable one towardthe other, and said screw means being constructed and adapted to clampthe conductor and the connector together to effectuate the remainingcircuit.

6. A connecting mechanism including a connector for connection to a wireof the circuit being measured, a lead conductor, a pair of circuitterminals disposed in parallel relationship and lying between theconnector and the lead conductor, insulating means separating thecircuit terminals, screw means extending through the connector, theterminals and the lead conductor for clamping together the conductor,the terminals and the connector as a pile and for clamping together incontact with one another the conductor and the connector when theterminals and the insulating means therebetween are removed, saidterminals and said insulating means as an assembly being provided with aslot extending thereinto from one edge of a dimension to encompass saidscrew means, and said terminals and insulating means being removablefrom the screw means and from between the connector and conductor whilethe screw means is maintained passing through the connector andconductor. I

7. A combination of a watthour meter and a demand meter including aconnector for connection to a wire of the circuit being measured, awatthour meter lead conductor, a pair of demand meter circuit terminalsseparated by an insulator and lying between the connector and the leadconductor with each contacted by one of said terminals, a screw passingthrough the conductor, the terminals, and the connector for clampingthem together as a pile, said terminals and the insulator therebetweenbeing slotted with the slots correlated and opening to one edge toreceiue the screw so that they may be removed together upon merelyloosening the screw, and

said conductor and connector then being relatively movable one towardthe other, and said screw means being constructed and adapted to clampthe conductor and the connector together to effectuate the watthourmeter circuit.

LOUIS A. PAINE. v KENNETH M. SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent or the original patent:

UNITED STATES PATENTS Number Name Date 2,337,212 Thomson et a1 Dec. 21,1943 2,391,479 Rivers Dec. 25, 1945 relatively movable one to-

